704.1.2.2 Identification of Hydrogen Piping Systems
Hydrogen piping systems shall be marked in accordance with ANSI A13.1. Markings used for piping systems shall consist of the name of the contents and shall include a direction-of-flow arrow. Markings shall be provided at all of the following locations:
- At each valve.
- At wall, floor and ceiling penetrations.
- At each change of direction.
- At intervals not exceeding 20 feet (6096 mm).